Source date be converted

HI, all,
I got very unusual problem.
My source is Oracle view, there is a column defined as varchar2(9), the value is '21-Mar-01', Source Qualifier data type is string length is 9. When I run the mapping, the data pushed out from Source Qualifier become '21/02/201', I didn't do any thing special on my source definition. If I change source qualifier field length to 10, it pushout '21/02/2010'. Does any body can give me some idea, why this happens and how to avoid this?